Venous thromboembolism (VTE) is a serious source of hospital morbidity and mortality. Chemoprophylaxis with heparin has been shown to reduce the occurrence of VTE, but it increases the risk of bleeding and it is uncomfortable to receive. For that reason, VTE prophylaxis should be reserved for patients at moderate to high risk of VTE and low risk of bleeding. However, identifying patients at low risk for VTE can be difficult, because most patients have at least one risk factor for VTE and there are no validated risk prediction tools for use in US hospitals. Instead, many hospitals have opted for a one-size-fits-all approach with near-universal prophylaxis, putting many patients at unnecessary risk of bleeding. However, to provide care that is truly patient-centered, US physicians face several challenges. First, there is no accepted risk calculator that they can use to estimate an individual patient's risk. Second, there is no validated risk calculator to estimate the risk of bleeding. Thid, the appropriate treatment thresholds for VTE or bleeding have not been identified (i.e. no one has defined what it means to be at low risk or at what level of risk the benefits of treatment outweigh the harms). Finally, risk calculators are not readily available at the point of care. As a result, prophylaxis rates have remained stubbornly low in some institutions, while in others the rate of prophylaxis is high, but the rate of inappropriate prophylaxis is also high. The aim of thi application is to use data from a large number of patients at the Cleveland Clinic to create tools that physicians can use to assess an individual patient's risk of both VTE and bleeding and to weigh those risks. An experienced team will develop and test these tools, and then incorporate them into a widely-used commercially available electronic health record in the form of a smart order set that will trigger an alert if the physician's order appears not to match the patient's rik. We will then assess the effects of the order set on physician behavior and patient outcomes using a randomized trial design. Examining the effectiveness of an electronic decision aid embedded in an EHR in routine clinical practice will test whether a smart order set can improve patient care by incorporating patient-specific factors into a complex decision process. This application builds upon our inter-disciplinary team's strong foundation of creating risk assessment tools and incorporating them into the EHR. Knowledge to be gained will inform best practices for VTE prophylaxis for millions of hospitalized medical patients each year and lead to other interventions for complex decision making involving patient-centered decisions.